Streptococcus pneumoniae is the most common bacterial cause of otitis media and acute respiratory infection and is estimated to result in over three million deaths in children every year worldwide from invasive diseases such as pneumonia, bacteremia, meningitis, and septicemia. The low efficacy of currently licensed pneumococcal polysaccharide vaccine has necessitated research into more efficient vaccines against pneumococcal disease. The long-term goal of this research is to develop a multi-component vaccine against pneumococcal disease, using genetically and antigenically conserved outer membrane proteins PspA, PsaA, and detoxified pneumolysin (PdB) from S. pneumoniae. Our hypothesis is that an effective pneumococcal vaccine should be composed of multiple conserved relevant antigens delivered preferably by a mucosal route in order to provide the best non-serotype-dependent protection against S. pneumoniae infection. Intranasal and transcutaneous immunization with replication-incompetent adenoviral vectors have proved to be efficient and simple for immunization. This non-invasive vaccine delivery will undoubtedly enhance the compliance of a vaccination program. In this project, adenovirus and plasmid expression vectors encoding PspA, PsaA and PdB will be constructed. In order to obtain an optimal vaccination protocol, immunization regimens with different combinations of adenoviral vectors through the intranasal and transcutaneous delivery modes will be compared with the intramuscular injection of plasmid expression vectors. The specific aims of this project are: Specific Aim#1: To develop a replication-incompetent adenovirus-vectored vaccine against Streptococcus pneurnoniae. Specific Aim #2: To compare the mucosal and systemic immunity elicited by adenovirus-vectored vaccine through intranasal and transcutaneous administrations with that elicited by plasmid expression vectors through intramuscular injection.